EAB larve, from infested ash tree in Des MoinesPhoto: Sue Danielson
(Des Moines, IA) -- A pest that's been killing Iowa's ash trees has now been confirmed in all 99-counties. Emerald ash borer destroys ash trees with two-to-four years after infestation. State forestry experts say signs of infestation include a thinning canopy, leafy sprouts shooting from the trunk or main branches, "s-" shaped tunnels under the bark and woodpecker damage. EAB was first discovered in Michigan in 2002. It's now been found in 37-states.
Insect samples collected from a declining ash tree in Armstrong (Emmet County) this month by Iowa DNR staffs were sent to the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) for confirmation. With positive confirmation, there are no remaining counties in Iowa without a detection.
The adult EAB beetle is approximately one-half inch long and metallic green. The larval stage of this insect tunnels through the wood just beneath the bark.
Landowners with ash trees on their property should begin to consider a course of action for at-risk trees, which are generally those within a 15-mile radius of a known infestation. Landowners and managers can wait and see what happens, remove declining ash trees and replace them with other species, or use preventive insecticide treatments to preserve and protect valuable and healthy ash trees. The best time to treat for EAB is in the spring from mid-April to mid-May. Insecticides are most effective when the ash tree is actively growing, and uptake is at its peak. Tree service companies can apply insecticide trunk injections through the summer if soil moisture is available.